Ignition system



Feb. 21 1950 Filed May 6,v 1944 I w. J. SPENGLER 2,498,305

' IGNITION SYSTEM 3 Sheets-Sheet 1 IN VEN TOR.

BY W

HTTORNEY Feb. 21, 1950 W. J. SPENGLER 2,498,305

IGNITION SYSTEM Filed May 6, 1944 I5 Sheets-Sheet 2 #10 INVENTOR.

HTTORNEY Feb. 21, 1950 w. J. SPENGLER IGNITION SYSTEM 3 Sheets-Sheet 3 Filed May 6 1944 INVENTOR.

QTTORNEY Patented Feb. 21, 1950 UNITED STATES PATENT OFFICE IGNITION SYSTEM Walter J. Spengler, Sidney, N. Y., assignor to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware Application May 6, 1944, Serial No. 534,475

1 12 Claims.

This invention relatesto ignition apparatus and more particularly to an ignition system for multicylinder internal combustion engines and means for shielding the same to prevent interference with radio reception and to afford physical protection therefor.

One of the objects of the present invention to provide a novel ignition system which overcomes ignition dimculties heretofore experienced in aircraft engines at high altitudes.

Another object of the invention is to provide an ignition system wherein electrical losses re.- sulting from the transmission of current at high voltages are reduced to a minimum.

Still another object is to provide a novelly constructed ignition system whereby the factor of safety against ignition failures is large compared with ignition systems now in common use.

A further object is to provide a system of the above character wherein the component parts may be made comparatively small and compact without sacrificing operating efficiency or safety in operation.

Another object is to provide an ignition systtem which may be applied to an internal combustion engine in a unique and novel manner to thereby simplify the radio shielding therefor and permit distribution of the parts and units of the system to avoid concentration of bulk.

Still another object is to provide a novel ignition system for an internal combustion .engine which may be satisfactorily shielded to avoid interference with radio reception by a min.- imum amount and bulk of lightweight shielding.

A still further object is to provide an ignition system wherein the circuit breakers may be operated at slower speeds in relation to the speed of the engine, thereby increasing the efiiciency and operating life of the circuit breakers and permitting greater engine speeds Without overworking the circuit breakers and ignition coils.

Another object is to provide an ignition systern, the novel parts of which may be readily adjusted to satisfactorily operate on different radial type engines having the master connecting rods thereof in different positions.

Another object is to provide a novel ignition system for a radial type engine having two or more banks of cylinders which is so constructed as to take best advantage of the available space on such engines without jeopardizin the ac.- cessibility and operating efficiency of the various parts of the system.

The above and furt r b e ts and v l a ture o e inve tion w l m e fu y app ar from the following detailed description when the same is read in connection with the accompanyin drawings. It is to be expressly understood that .the drawings are for the purpose of illustration only and are not intended to define the limits of the invention, reference being primarily had for this latter purpose to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a diagrammatic front elevation illustrating one form of the ignition system comprehended by the present invention mounted on a double row radial type engine;

Fig. 2 is a diagrammatic top plan view of the engine and ignition system of Fig. 1 with parts of said engine removed; Y

Fig. 3 is a diagrammatic side elevation of said engine and system with parts of said engine re;- moved; and,

Fig. 4 is a schematic wiring diagram of said system with parts of the latter shown diagrammatically.

The single embodiment of the novel ignition system comprehended by the present invention is illustrated in the drawings, by Way of example, in a form adapted for use on a dual-ignition, l8-cylinder, four stroke cycle, radial type engine having two banks of nine cylinders each, the cylinders of one bank being in staggered relation with respect to the cylinders of the other bank. ,As illustrated, the engine which is shown diagrammatically and with parts removed comprises a rear or No. 1 bank of nine radially dis.- posed cylinders it and a front or No. .2 bank of nine radially disposed cylinders ll. Each of the cylinders in has a spark plug l2 in the front thereof and a spark plug [3 in the rear thereof while each of the cylinders II has a front plug it and a rear plug l5.

For the purpose of increasing the safety and efficiency of engine operation, particularly in the rarified atmosphere at high altitudes, high voltage electrical current is supplied to each spark plug of the engine from a separate ignition or transformer coil 24 (Fig. 4) mounted relatively near the spark plug which it serves. In the interest of attaining minimum weight and utilizing a minimum of space, while at the same time taking best advantage of the space avail.- able on the engine, coils 24 .are mounted on the engine in a novel manner whereby the combined weight thereof is advantageously distributed. In the form shown coils 2 are divided into groups of four and each gr-Qup is enclosed for radio shielding and protection purposes in a metallic casing 25. One of said coil casings is mounted between each pair of adjacent cylinders II of the front or No. 2 bank of cylinders where the same are readily available for inspection and removal or replacement. Coil casings and the installation of the coils 24 therein may be of the type disclosed in and in accordance with the teachings of Spengler, U. S. Pat. No. 2,412,102. Each coil casing is shown, by way of example, asbeing supported by a metallic strap 26 (Fig. 1), the threaded bolt-like ends of which extend outwardly through valve tappet covers 21 which are secured to the engine cylinders in any well known manner. Nuts 28 engage the threaded ends of supporting strap 26 and hold the same in position to support the coil casing 25. The side of said casing opposite that engaged by strap 26 is engaged by curved extensions 29 of valve tappet covers 21. A layer of resilient material 30 is preferably interposed between casing 25 and the supporting means 26, 29 to reduce the effects of engine vibration and relative movement of the adjacent engine cylinders.

The rear wall of each coil casing 25 is preferably provided with four sockets adapted to receive connector plugs of the Cannon or other suitable type from four of the engine spark plugs, each of said sockets being electrically connected to the high potential end of the secondary winding 3| (,Fig. 4) of one of the coils 24. The leads 32 between said connector plugs and the engine spark plugs are shielded by flexible metal conduits 33 (Fig. 1), said leads and shielding conduits being preferably detachably connected with the spark plugs and the rear of casings 25 in any suitable manner well known in the art, one suitable form of connection to the spark plug being illustrated in Frei Patent No. 2,312,757, dated March 2, 1943. The coils housed in each casing 25 having the secondary windings 3| thereof connected through leads 32 to the spark plugs I2 and I3 in a cylinder I6 of the rear bank or row of cylinders and the spark plugs I4 and I5 of a cylinder II of the front bank, as is best illustrated in Fig. 2. The high tension leads 32 are sufficiently short to minimize the line losses and the capacity effects, thereby reducing the power which must be generated and increasing the operating characteristics of the spark plugs. If desired, all of the shielding conduits 33 and the leads 32 therein may be made of equal length so as to be interchangeable and hence reduce the number of spare parts required in the field or at distant military bases.

Electric current at relatively low or generated voltage, such as approximately 300 volts, is supplied to the primary windings 34 (Fig. 4) of coils 24 in each casing 25 through leads 35 that extend from current distributing means to be hereinafter described through a tubular radio shielding manifold 36 which is circle-like and is secured to and electrically grounded through the nose or front of the engine casing 31 or cylinders II by suitable brackets or clamps 3'! in a familiar manner well known in the art. A short detachable shielding conduit 38 which is preferably flexible connects manifold 36 with the front of each coil housing 25. The four leads 35 which extend through each conduit 38 are preferably connected with the primary windings 34 of coils 24 in casings 25 through a four prong "Cannon plug or other suitable plug and socket connector 39. Leads 35, which are in the form of insulated cables, extend from shielding harness manifold 36 through shielding conduits 40, 46, which are preferably flexible for at least a part of their lengths, to a pair of current distributing units 4 I ,4 I mounted on opposite sides of the nose of the engine casing 31. Units 4| and 4| may be of the type illustrated in Frei and Purdy U. S. Pat. No. 2,445,570.

Distributor units 4I,4I are so constructed as to distribute current from a suitable source to be hereinafter described to the spark plugs in a novel manner which permits the engine to operate at high speeds with maximum efficiency and without physically or electrically overtaxing the elements of the ignition system. In the form shown, distributor unit 4I comprises two sets of nine circularly arranged contacts 42 and 43 to which leads 35 are connected and two rotatable contact elements 44 and 45 which are preferably mounted on a common shaft and operatively connected with the engine to be rotated at one-half engine crankshaft speed. Unit M is identical and interchangeable with unit M, the corresponding parts being indicated by the same letter or the same numerals followed by a prime mark In the interest of safety, that is, as a protec tion against complete engine failure in the event of the failure of one of the distributor units and in the interest of simplicity, one of said units is connected to and controls the distribution of current to the front spark plugs I2 and H4 in all of the cylinders II], II, whereas the other distributor unit controls the distribution of current to the spark plugs I3 and I5 in the rear of all the cylinders. As shown in Fig. 4, distributor unit 4I distributes current to the front spark plugs, whereas the distributor unit 4 I distributes current to the rear spark plugs. The rotary elements or contacts of both distributor units M, 4 I are synchonously driven by the engine so that the front and rear spark plugs in each engine cylinder will be supplied with current and hence be fired simultaneously or substantially so to ignite the combustible charge in the cylinder.

In order to make the distributors 4! and 4| interchangeable, as small as possible and readily adjustable for use on different engines having the master connecting rods thereof in various positions, the corresponding rings of contacts 42,42 in both distributor units are connected by leads 35 with the coils 24 which supply high tension current to the spark plugs I2, I3 of the rear bank of cylinders I0 and the corresponding rings of contacts 43,43 of both distributor units are connected with the primary windings of the coils 24 which have the secondaries thereof connected with the spark plugs I4, I5 of the front bank of cylinders I I. Current supplied through rotatable distributor contacts 44,44 and 45, 45' will accordingly be distributed in such a manner as to fire cylinders in the rear and front banks alternately, that is between the firing of successive cylinders in the rear bank a cylinder of the front bank will be fired. This novel means for distributing the current to the spark plugs of a double row radial engine makes it possible to materially reduce the circumference of the rings of distributor contacts and makes it possible, by easy adjustment of the compensated cams of the circuit breaker means described below, to take care of changes in the position of the master connecting rod of radial type engines without altering the construction of the distribution units.

Each of the distributor units may also incorporate two sets of separable circuit breaking contacts M, one set for each rotatable distributor contact and its associated .ring of stationary contacts. The opening and closing of each set of circuit breaker contacts M is controlled by a separate cam (not shown), said cams preferably being of the nine-lobe compensated type, and mounted on the same shaft as the associated distributor elements M, 45 or 44, '45 for rotation therewith. One contact of each of the main circuit breakers M is connected to ground, as at 46, while the other contact of each pair is connected in parallel with a rotatable distributor c'ontact, such as contact M, to a source of electrical energy which will be hereinafter described. A condenser C is preferably connected across each set of main circuit breaker contacts M to minimize arcing across the latter. Each of the distributor units MAI also includes two sets of booster circuit breaker contacts B which be connected in circuits to be more fully described hereafter.

The source from which electrical energy is supplied to distributor units 4i and H for distribution to the primary windings of coils 24 and, hence, to the spark plugs may be of any suitable type known to the art but is preferably constituted by a novel magneto'generator M that may be mounted on the rear of the engine casing and driven by the engine crankshaft. One suitable form of generator for use in the present ignition system is disclosed in Rolland M. Purdy U. S. Patent No. 2,483,667. Said generator is the equivalent of two double magnetos and comprises two fourpole magnetic rotors mounted on a common shaft driven from the engine crankshaft at one and one-eighth crankshaft speed. Each magnetic rotor is associated with two two-pole stators on each of which is wound a primary induction coil. The four induction coils 48, 49, 5a and 5! are shown diagrammatically in Fig. 4. The arrangement of the magnetic rotors and the stators on which the induction coils are wound is such that coils 48 and 49 will be periodically simultaneously energized to supply energy for firing spark plugs l2 and !3 of the rear bank of cylinders It and coils "50 and 5| will be periodically simultaneously energized for supplying energy to fire the spark plugs f4 and [5 of the front bank of cylinders l I. Coils '48, 49 and coils 5i}, 5! are, of course, alternately energized in timed relation. This may be effected by angularly displacing one of the magnetic rotors with respect to the other on their common shaft. Thus, if the coils 48 and 50 are diametrically disposed with respect to coils 29 and 5|, by displacing or staggering one rotor 45 with respect to the other, nine dual sparks may be obtained for each revolution of the engine crankshaft when the rotor shaft is driven one and one-eighth times as fast as said crankshaft, thus satisfying the ignition requirements for an iii-cylinder four cycle engine. The rapidity with which the induction coils of the magneto need be energized and re-energized is thus kept within such limits as to insure effective operation at high speeds and also insure long life of the coils.

The ungrounded or output ends of the induction coils of the magneto generator 4'! are preferably connected "with distributor units 4!, M through a six prong detachable plug and socket connector 52, the plug portion of which is preferably mounted in the end of a flexible shielding conduit 53 which is either permanently or-detachably connected to shielding harness manifold 3t.

The magneto may also be provided with a six 6 prong plug and socket connector 54 through which each of the induction coils of the magneto may be connected with separable switch contacts in a multiple ignition switch 55. vThe latter is preferably provided with four switches 51 through which the magneto induction coils may be individually grounded at 58. to render one or more of the same inoperative to supply current to the distributor units and, hence, to induction coils 24. Multiple switch 55 also includes a switch 58 which is adapted .for controlling a booster or starting circuit in a manner .to be more fully described hereafter, one contact of said switch also being connected to ground at 56.

Since the magneto induction coils are all connected in the same manner with the elements of distributor units 4! and 4| which are in circuit therewith, it will be sufficient for a full understanding of the operation and the remaining structure of the novel ignition system comprehended by the invention to trace the connections or circuit from one of said coils and explain the operation of that circuit. The high potential end of coil 48, for example, is connected through plug connector 52 to a lead 59 that extends through conduit 53, manifold 35 and conduit all into distributor unit 4|. Within this unit, lead 59 branches into leads it and GI which connect with rotary distributor contact 44 and the insulated contact of one of the main circuit breakers M, which may be designated by the numeral 62. The connections between lead Gil and rotary contact 44 and between said contact and stationary contacts 42 may be effected by suitable carbon brushes or the like. Connections from coils 49, 5c and 5| to rotatable contacts A l, 45 and 45, respectively, may be made in the same manner as the connection between coil 48 and contact arm 44, each circuit having a circuit breaker M in parallel with the contact arm thereof.

'It will thus be clear that when current ata relatively low voltage is induced in coil '48 while the circuit breaker contact 62 engages its companion contact'63 to close the circuit to ground, and while switches 51 are open,saidcurrent follows the path of least resistance through said contacts to ground at 45. The current in coil 48 approaches its peak value at about the instant it is desired to fire a spark plug l2 in one of the engine cylinders I0. At or near this time the circuit breaker contacts 62, 63 are separated by a cam or other suitable means, thereby causing a sudden rise or surge of current at a voltage of approximately 360 volts through lead 60, rotary P distributor contact 54, the stationary distributor contact '42 then engaged by contact 44, a lead and 'a primary winding 34 of a coil 24. This surge or sudden rise of current in the primary winding of the coil induces a current at a higher voltage in thesecondary winding 3! of the same coil and is effective to create a spark across the terminalsof a spark plug l2, the particular spark plug across which the spark occurs being dependent upon the particular distributor contact 42 with which rotary contact 44 happens to be in engagement.

The rotatable parts of magneto ll and distributor units ll, M are so synchronized witheach other and with the engine that the two spark plugs in each cylinderare periodically fired simultaneously and the spark plugs in the several cylinders are fired in a predetermined time sequence at intervals determined by the spacing of the lobes on the circuit breaker camswhich control the separation of the contacts of the main circuit breakers M. The two sets of circuit breaker contacts M in distributor unit 4! are alternately opened and the two sets of circuit breaker contacts M of distributor unit 4! are alternately opened in synchronism with those in unit 4| to thereby produce two simultaneous sparks in each cylinder.

In order to avoid unnecessary complication of the drawings by showing the numerous connections between all of the circularly arranged stationary distributor contacts of the two distributor units 4|, 4| and the primary windings 34 of coils 24, the connections to only one group of four coils is illustrated in Fig. 4 as typical of the connections to all of such groups. However, the cylinder and spark plug with which each coil 24 is associated is indicated in Fig. 4 by an encircled numeral followed by the letter F or R, said letters designating front and rear, respectively. Thus, the encircled numeral 14R designates the rear spark plug in cylinder #14 and the encircled numeral [4F designates the spark plug mounted in the front of cylinder #14. The cylinders ll! of the rear bank on the engine are arbitrarily designated by the numerals #1, #3 #17, and the cylinders ll of the front row or bank are designated by the numerals #2, #4 #18 (Fig. 1). Since the firing order of the cylinders does not correspond with the numbers assigned to designate the cylinders, said firing order is indicated in Fig. 4 by encircled numerals 1 to 18, inclusive, and the stationary contacts of the distributor units are correspondingly numbered to indicate which of said contacts are connected to particular transformer coils 24. For example, the front and rear spark plugs in cylinder #14 are fired 12th in the successive firing of the various cylinders, assuming that cylinder #1 is the first to fire. Accordingly, the coil for the rear spark plug in cylinder #14 is connected with the No. 12 stationary contact 43 in distributor unit 41' which controls the distribution of current to all rear spark plugslS and 15 and the coil for the front spark plug in said cylinder #14 is connected with stationary distributor terminal No. 12 in distributor unit 4! which distributes current for all front spark plugs I2 and M. By way of further example, the coils for the front and rear spark plugs in cylinder #15 are connected with the stationary terminals No. 17 in distributor units 4!, 4|, respectively. Likewise, the coils associated with the front and rear spark plugs in cylinder #3, which is eleventh in the firing order, are connected with stationary distributor terminals No. 11 in units M and 4 I, respectively. It may be noted also that the firing order of the cylinders as indicated in Fig. 1 is such that the cylinders of the front and rear banks fire alternately, The firing order in terms of cylinder numbers being as follows:

It may be seen by tracing the connections in Fig. 4 that magneto coils 18 and 59 are connected with rotary distributor contacts 44 and 55, respectively, and main circuit breakers M in distributor unit 4! and that magneto coils 49 and 5! are connected to rotary distributor contacts 64' and 45', respectively, and main circuit breakers M in distributor unit 4 l the rotary distributor contact and the circuit breaker M in each circuit being connected in parallel with respect to the magneto coil in the same circuit. Accordingly, magneto coils 48 and 49 are simultaneously energized by a common magnetic rotor or magnetic flux distributing rotor for supplying energy 8 to the front and rear spark plugs, respectively, of the front bank of cylinders ll while coils 50 and 5! are similarly simultaneously energized by another rotor, alternately with the coils 48 and 49, for supplying energy to the front and rear spark plugs, respectively, of the rear bank of cylinders II).

If it is desired to render ineffective or inoperative the front or rear groups of spark plugs in either bank of cylinders, this may be done by closing the appropriate switch or switches 51. This will connect one or more of the magneto coils G8 to 5! to ground at 56 and render the same ineffective to supply sufficient energy to the spark plugs for firing the same, as is well understood in the art.

Any suitable means may be provided for supplementing or replacing magneto 4'! for starting the engine, said magneto being ineffective for this purpose'at the low speeds at which the crankshaft is turned by the starting motor. In the form shown, two booster coils 55 and 65 are provided in a metallic shielding casing El which may be connected with the magneto casing through a metallic conduit 58. Coils 65 and 66 are connected into the above described ignition system for supplying energy to the front spark plugs I2, I ii in cylinders in and H, respectively, but if desired these coils could be connected to supply the rear spark plugs of both banks of both cylinders or the front spark plugs in one bank and the rear spark plugs in the other. Since the two booster coils and the connections thereto are substantially identical, the construction, connections and operation for only one coil will be hereinafter described and traced.

Booster coil 55, for example, comprises a selfinduction winding 59, one end of which may be connected to ground at 55 through a lead 19 which passes through a plug and socket connector H and plug and socket connector 54 to switch contacts 58 in switch 55. The other end of the winding 59 is connected through a suitable fuse l2, buzzer contacts l3 and starter switch M to a battery 15 or other suitable source of electrical energy. Said other end of winding 69 is also connected through a resistance 1'6 and a lead H which passes through connectors "H and 52 to one of the contacts 18 of a booster breaker B in distributor unit Al. The other contact 19 of said circuit breaker is connected to lead 6! between main circuit breaker 52, 63 and rotary contact arm 45. Circuit breaker l8, l9 and circuit breaker 62, 63 may be operated by the same rotating cam. Thus, when switches 58 and M are closed, current may flow from battery 15 through normally closed buzzer contacts 13 and winding 69 to ground at 55 in switch 55. The current fiow through winding 59 establishes a magnetic field which is effective to separate the contacts of circuit breaker 13, thereby opening the circuit through the winding. The opening of this circuit results in a collapse of the magnetic field set up by the current flow in winding 69 and, hence, results in a reclosing of the buzzer contacts 13 by a spring or other suitable resilient means. As is well understood in the art, this operation is repeated in relatively rapid succession as long as the switches 58 and. M are closed.

Upon each collapse of the magnetic field about winding 59, the latter produces an inductive kick, so to speak, which sends a sudden surge of current through resistance 16 and lead 11 to booster breaker l8, 19. If the latter and circuit breaker 32, 53 are both in closed position, this self-induced current from winding 69 flows to ground at 46. If; on the other hand, the contacts 18-, 19 are in closed position and contacts 62, 63' are not engaged, the surge of current flows through rotary distributor arm or element 44 to one of the coils 24 and, hence, creates a spark at one of the spark plugs M in the same manner as heretofore fully described in connection with the operation of the main ignition circuit. Spark plugs l2 are fired alternately with spark plugs M by booster coil (it in the same manner, the circuits being controlled by the other circuit breakers shown in distributor unit Mi and the current flow being through distributor arm. 45. to the. coils connected with the distributor terminals 43.

When the engine starts and picks up speed, the magneto 41 becomes. effective to fire the spark plugs in. the manner heretofore. described. Switch 14 may then be either manually or automatically opened, thereby rendering the booster coils inoperative.

Ifdesired, the windings of coils 65 and 65. may be replaced by transformer windings havin the primaries thereof permanently grounded in cas ing 6'! and the secondaries thereof connected through normally open, magnetically operated relay switches to the booster circuit breakers B in one of the distributorunits. The windings for the. solenoids which operate the contacts of the relay switches may be connected directly to battery 1-5 when switch 1.4 is in closed position. The relay switches serve to disconnect the booster coils from the main ignition system during normal operation of the engine.

There is thus provided a novel ignition system for internal combustion engines, the novel construction and operation of which adds to the efiiciency and balance of the engine and makes it possible to reduce the sizeand weight of each of the various parts of the system. Additionally, there is provided an ignition system, the parts of which may be advantageously arranged on the engine for purposesv of installation, inspection and repair and which may be radio shielded in a simple and eific-ient manner with a minimum of weight and a. minimum number of shielding conduits. Furthermore, the novel system comprehended also provides maximum safety against engine failures 2,11d','h81'106, against injury to personnel and property, particularly at high altitudes, the current generating and distributing means beingv such as to make it relatively easy to segregate and discover the source of any partial failure of the system.

Although only a limited number of embodiments of the invention are illustrated and described in the foregoing drawings. and specification, it is to be expressly understood that the same is not limited thereto. For example, the various parts of the ignition system, such as the magneto, coils and distributors, may be arranged d-ifierently onthe engine and said parts may be constructed quite dififerently than illustrated and described without departing from the spirit and scope of the invention in its broadest aspects as the same will now be understood by those skilled in the art. For a definition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is:

1. An ignition systemfor a dual ignition, double bank, radial type engine having the cylinders of one bank arranged around the crankshaft in staggered relation tothe cylinders of the other bank, comprising a magneto includin two magnetic rotors mounted on a common shaft with the magnetic poles thereof in angularly staggered relation, two pair of induction coils associated with said rotors and adapted to be alter nately energized thereby, the coils of each pair being simultaneously energizedby the rotor associated' therewith, means for distributing electrical energy from one coil of each of said pairs to spark plugs in all of the engine cylinders, and other means for distributin electrical energy from the other coil of each of said pairs to spark plugs in all of the engine cylinders.

2'. In combination with an internal combustion engine having a plurality of banks of cylinders, each bank having a plurality of radiallydisposed cylinders, an ignition system comprising a pair of spark plugs in each of said cylinders, each pair of spark plugs consisting of a front plug and a rear plug, a housing enclosing four ignition coils mounted near each pair of adjacent cylinders of the front bank, means connecting the secondary windings of said coils to the pairs of spark plugs in a cylinder of the front bank and a cylinder of the rear bank adjacent thereto, twoignition distributors, means connecting the primary windings of said coils to the output terminals of said distributors, the coils connected with the front spark plugs being connected to the terminals of one distributor and the coils connected with the rear spark plugs being connected to the terminals of the other distributor,

each of said distributors having two input terplugs in the other bank of cylinders, current generating means for periodically supplying elec trical energy simultaneously to an inputterminal of each distributor, and other current generating means for supplying electrical energy simultaneously to the other input terminals of said distributors.

3. In an engine having a plurality of radially disposed cylinders arranged in two axially spaced banks, an ignition system comprising a front spark plug anda rear spark plug in each cylinder, a pair of ignition coils mounted adjacent each cylinder, means connecting the secondary winding of each of said coils to a spark plug in an adjacent cylinder, a distributor having the output terminals thereof connected to. the, primary windings of the coils connected with the front spark plugs, another distributor having the output terminals thereof connected with the primary windings of the coils connected with the rear spark plugs, each of said distributors having two input terminals each connected: to a rotary distributor element adapted to successively cooperate with said output terminals, current. generating means for periodically supplying electrical energy simultaneously to an input terminal of each distributor, other current generating means for supplyin electrical energy simultaneously to the other input terminals of said distributors, the energy impulses from one 'of said current. generating means alternating with the energy impulses from the other current. generating means, and a. circuit breaker connected in parallel with each of said rotary distributor elements.

4-. In combination with an. internal combustion engine having 'a plurality of banks of cylinders, each bank having a plurality of radially disposed cylinders, an ignition system comprising a front and a rear set of spark plugs in the cylinders of each bank, separate means for generating electrical energy for firing the front and rear sets of spark plugs of each bank of cylinders, a distributor connected to certain of said means for distributing energy therefrom to the front sets of spark plugs in all of said banks, and another distributor mechanically independent of the first one and connected to the other of said means for distributing energy therefrom to the rear sets of spark plugs in all of said banks.

5, In combination with an internal combustion engine having a plurality of radially disposed cylinders arranged in a plurality of banks, an ignition system comprising a front and a rear spark plug in each of said cylinders, separate current generating means for supplying electrical energy to the spark plugs in each bank of cylinders, means connected to certain of said generating means for distributing energy generated thereby to' the front spark plugs in predetermined sequence, and other means mechanically independent of said last-named means and connected to the other of said generating means for distributing energy generated thereby to the rear spark plugs in predetermined sequence, said current generating means and said distributing means being adapted to supply energy simultaneously to the front and rear spark plug in each cylinder.

6. In combination with an internal combustion engine having two banks of radially disposed cylinders, an ignition system comprising a pair of spark plugs in each of said cylinders, current generating means for simultaneously supplying energy to the spark plugs of each pair, means for distributing energy from said current generating means to one of the spark plugs of each pair, and other means mechanically independent of said distributing means for distributing energy from said current generating means to the other spark plug of each pair, both distributing means being so constructed that the pairs of spark plugs in the cylinders of one bank will be successively fired and alternately with the pairs of spark plugs in the cylinders of the other bank.

7; In a low voltage distribution ignition system for an internal combustion engine, two groups of cylinders, the combination of a pair of spark plugs in each cylinder, a first current generating means for supplying electrical energyto the spark plugs in one group of said cylinders, a second current generating means for supplying energy to the spark plugs in the other group of said cylinders, the energy impulses supplied by said first current generating means alternating with the energy impulses supplied by said second current generating means, distributor means for distributing energy from both of said first and second current generating means to one spark plug of each pair, and other distributor means for distributing energy from both of said current generating means to the other spark plug of each pair.

8. In an ignition system for an internal combustion engine, two double magnetos for generating alternate current impulses, an ignition distributor for distributing current generated in one coil of each of said magnetos, an ignition distributor for distributing current generated in the other coil of each magneto, each of said distributors including two rotary distributing elements mounted on a common shaft, circuit breaker means for each of the magneto coils including cam means on said distributor shafts, and two spark plugs in each cylinder of the engine, one spark plug in each cylinder being connected with one of said distributors and the other spark plug in each cylinder being connected with the other distributor.

9. In an ignition system for a multi-cylinder internal combustion engine, two double magnetos having the magnetic flux distributing rotors thereof mounted on a common shaft, each rotor being adapted to intermittently simultaneously energize two coils, the coils associated with one rotor being energized alternately with the coils associated with the otherrotor, a pair of ignition distributors each comprising a rotatable shaft and two rotary distributor elements on said shaft, each of said elements being connected with a different oneof the magneto coils and one of said elements of each distributor bein connected with the coils of the same magneto, a circuit breaker connected in parallel with each of said elements, and means on said shafts for periodically operating said circuit breakers in timed relation.

10. In an l8-cylinder internal combustion engine having two banks of nine radially disposed cylinders each, the cylinders of one bank being angularly displaced relative to the cylinders of the other bank, an ignition system comprising two double magnetos each having a four-pole flux distributing magnetic rotor, means for connecting said rotors to the crankshaft of the engine to be driven at 1 times the speed of the crankshaft, a pair of distributors each having a shaft driven by the engine at /2 crankshaft speed, one of said distributors being adapted to distribute energy from one coil of each. of said magnetos to spark plugs in all of the cylinders and the other of said distributors being adapted to distribute energy from a different coil of each magneto to other spark plugs in all of said cylinders, and means on said distributor shafts for operating circuit breakers in circuit with said coils.

11. In an 18-cylinder internal combustion engine having two banks of nine radially disposed cylinders each, an'ignition system comprising two current generating systems each comprising a four-pole magnetic flux distributing rotor and two coils adapted to be simultaneously energized, the coils associated with one of said rotors being energized alternately with the coils associated with the other of said rotors, means for drivably connecting said rotors to the engine to be driven at 1 times the speed of the engine crankshaft, two distributors each having a shaft drivably connected with'the engine for rotation at the speed of the crankshaft, one of said distributors being adapted to distribute energy from one coil of each of said systems to a set of spark plugs comprising one spark plug in each cylinder and the other distributor being adapted to distribute energy from the other of said coils to a second set of spark plugs comprising a spark plug in each of said cylinders, whereby two spark plugs in each cylinder are fired simultaneously in timed relation with the firing of the spark plugs in each other cylinder and the spark plugs in the cylinders of one bank are fired alternately with the spark plugs in the cylinders of the other bank, and means on said distributor shafts for operating circuit breakers connected in circuit with said coils.

12. In combination with an internal combustion engine having a plurality of banks of cylinders, each bank having a plurality of radially disposed cylinders, an ignition system comprising two sets of spark plugs in the cylinders of each bank, each cylinder having two spark plugs therein, separate means for generating electrical energy for firing all of the spark plugs in each bank of cylinders, a distributor connected to said generating means for distributing energy therefrom to one set of said spark plugs in all of said banks, and another distributor connected to said generating means for distributing energy therefrom to the other set of spark plugs in all of said banks.

WALTER J. SPENGLER.

REFERENCES cI'rEn The following references are of record iii the file of this patent:

UNITED STATES PATENTS Number Name Date 1,471,345 Milton e Oct. 23, 1923 1,616,939 Woolson flee-=22; Feb. 8, 1927 1,907,512 Davis May 9, 1933 2,082,800 Holliday l l June a, 1937 2,105,791 Mascuch Jan. 18, 1938 2,166,420 Robertson ...-i.. s July 18, 1939 2,234,579 Robertson Mar, 11, 1941 2,236,396 Bryan et al -11-; Mar. 25, 1941 2,278,481 Peters et al. Apr. 7, 1942 2,287,134 Robertson June 23, 1942 2,287,135 Robertson June 23, 1942 2,290,501 Spengler et al July 21, 1942 2,291,051 Mascuch July 28, 1942 

